Add information on book printing and PDFs

PRINTING.md

@@ -0,0 +1,32 @@
+Printing These Books
+====================================================================================================
+
+These books have been formatted to be print friendly (using CSS media queries). That means that you
+should be able to print them directly from your browser of choice (usually Ctrl-P on Windows and
+Linux, or Cmd-P on Mac).
+
+We've taken some care to set up sensible page breaks in the printed versions, though you still may
+find a few odd artifacts here and there. For example, the latest version of Markdeep can let
+images/figures and their captions land on different pages. This issue has been reported, and there
+may be a fix in the works for this.
+
+
+Pre-Printed Books
+------------------
+I've gone back and created PDFs for each book for versions v2.0.0, v3.0.0, v3.2.3. You can find
+these in the assets section of each release on the [GitHub releases page][releases]. We will include
+PDFs for all books with all future releases.
+
+
+Creating PDFs of These Books
+-----------------------------
+If you wish to create your own PDF of any of these books (like for a version currently in
+development, or to test the results on your own changes), the easiest way is to use a save-to-PDF
+print driver. When viewing a book in your browser, issue your browser's print command, and look
+through the available destination printers. Hopefully you'll find a save-to-PDF printer already set
+up and available. If not, you should be able to search for and find such a print driver for your
+particular operating system.
+
+
+
+[releases]: https://github.com/RayTracing/raytracing.github.io/releases

README.md

@@ -27,8 +27,8 @@ we strongly recommend that you jump above the v4 train.
   - [Ray Tracing: The Next Week][web2]
   - [Ray Tracing: The Rest of Your Life][web3]
 
-These books have been formatted for both screen and print. For printed copies, or to create PDF
-versions, use the print function in your browser.
+These books have been formatted for both screen and print. For more information about printing your
+own copies, or on getting PDFs of the books, see [PRINTING.md][] for more information.
 
 
 Project Status
@@ -202,6 +202,7 @@ _**please review the [CONTRIBUTING][] document for the most effective way to pro
 [implementations]: https://github.com/RayTracing/raytracing.github.io/wiki/Implementations
 [milestone 16]:    https://github.com/RayTracing/raytracing.github.io/milestone/16
 [milestone 19]:    https://github.com/RayTracing/raytracing.github.io/milestone/19
+[PRINTING.md]:     PRINTING.md
 [v3.2.3]:          https://github.com/RayTracing/raytracing.github.io/releases/tag/v3.2.3
 [web1]:            https://raytracing.github.io/books/RayTracingInOneWeekend.html
 [web1-v3]:         https://raytracing.github.io/books/v3/RayTracingInOneWeekend.html

books/RayTracingInOneWeekend.html

@@ -69,6 +69,9 @@
 Peter maintains a site related to this book series at https://in1weekend.blogspot.com/, which
 includes further reading and links to resources.
 
+These books have been formatted to print well directly from your browser. We also include PDFs of
+each book [with each release][releases], in the "Assets" section.
+
 If you want to communicate with us, feel free to send us an email at:
 
   - Peter Shirley, [email protected]
@@ -4186,6 +4189,7 @@
 
 [discussions]:        https://github.com/RayTracing/raytracing.github.io/discussions/
 [gfx-codex]:          https://graphicscodex.com/
+[releases]:           https://github.com/RayTracing/raytracing.github.io/releases/
 [repo]:               https://github.com/RayTracing/raytracing.github.io/
 [square-pixels]:      https://www.researchgate.net/publication/244986797
 

books/RayTracingTheNextWeek.html

@@ -31,6 +31,9 @@
 you want a weekend project. Order is not very important for the concepts presented in this book, and
 without BVH and Perlin texture you will still get a Cornell Box!
 
+These books have been formatted to print well directly from your browser. We also include PDFs of
+each book [with each release][releases], in the "Assets" section.
+
 Thanks to everyone who lent a hand on this project. You can find them in the acknowledgments section
 at the end of this book.
 

books/RayTracingTheRestOfYourLife.html

@@ -41,6 +41,9 @@
 
 As before, https://in1weekend.blogspot.com/ will have further readings and references.
 
+These books have been formatted to print well directly from your browser. We also include PDFs of
+each book [with each release][releases], in the "Assets" section.
+
 Thanks to everyone who lent a hand on this project. You can find them in the acknowledgments section
 at the end of this book.